Estimation of Electricity Savings Achievable with Automatic Artificial Lighting According to Window Orientation and Size

Daylight in workplaces is necessary for the psychophysical health of the occupants and, if its level is adequate, it can reduce electrical costs of artificial lighting. This study presents some realistic estimates of the electrical savings that could be achieved from artificial lighting. The scenario is to replace the classic lighting system with one that can be controlled automatically to maintain the illuminance setpoint. The convenience of this type of replacement depends on the location, size and exposure of the window. INLUX-DBR is the experimentally validated code used to perform the simulations. The place analysed for the study is an office room simulated in two localities: Cosenza, in the south of Italy, and Milan, in the north of Italy. The energy savings values are calculated as a function of the exposure and of the area of the window. The results are almost independent of latitude and are representative of the whole Italian territory. Savings of up to 97% can be achieved for south-facing windows compared to the condition of continuous lighting in an office.